It is a widely known fact that hand-held blenders of the type referred to by the present invention have a motor assembly that includes an electric motor that can be electrically powered and which constitutes the drive part, with an output shaft, and a tool shank that, when correctly coupled to said motor assembly, allows the movement of the motor to be transmitted to the proximal end of the shaft that runs along the length of said shank, and which on its opposite end, or distal end, has a blade for cutting and blending the food to which it is applied.
As will be understood, it is necessary for the coupling between the tool shank and the motor assembly to have suitable characteristics that guarantee sufficient safety conditions during its use, but which also allow the tool shank to be released, i.e. allow the tool shank to be separated from the motor assembly with a view to subjecting the former to the necessary operations to keep it in good conditions of hygiene and cleanliness, in addition to any other maintenance operation or even replacement of the tool shank in the event of it breaking or suffering irreparable damage.
The normal connection between a tool shank and motor assembly in a blender of the type considered here currently consists of the provision of a screw or bayonet type connection. Screw and bayonet connections can be designed in such a way that they are more or less easy to engage/disengage. However, both types of coupling, assembly and fastening have certain drawbacks in practice, because if these connections are performed in such a way that they are easy to engage/disengage, they occasionally present the problem that they accidentally become disengaged while the blender is in use, which clearly represents a hazard for the user; on the other hand, if the coupling is performed in such a way that it is difficult for the user to engage/disengage, this presents a different set of problems, as releasing the tool shank would mean applying excessive force, therefore making it impossible for the user to separate the two parts.
Bearing in mind the drawbacks that exist in the current state of the art with regard to said hand-held blenders, in particular with respect to engaging/disengaging the tool shank and the motor assembly, the main objective proposed by the present invention is to design a coupling that allows the user to perform the coupling or releasing operation easily, conveniently and quickly, yet at the same time with absolute certainty that the connection between the two parts is stable, without the possibility of accidental separation while it is in use, and with the user's full knowledge that the connection has been correctly established.
This objective has been fully achieved by the releasable coupling arrangement of the invention, which will be explained below, and the characteristics of which are contained in the characterising part of the attached claim 1.
Essentially, the coupling proposed by the invention is of the type that uses screw connections between the inner nut on the bell at the top of the tool shank and the cylindrical projection or nozzle that extends from the motor assembly surrounding the drive shaft that is connected to the motor, said screw connection corresponding to a design of the quick coupling type, with the particularity that the motor assembly itself additionally includes, in a position closely adjacent to said output nozzle, a plastic piece that constitutes a retaining click-in element, for the purpose of which said plastic piece, which can give elastically to a certain degree, presents a rounded-edged transversal v-shaped bend that substantially projects from the plane of the end face of said motor assembly. In turn, the bell part of the tool shank, in addition to having a threaded section on its coupling nut that can be fitted to the threaded section formed on the outer surface of the output nozzle of the motor assembly, has its inner area divided into sectors by means of radial partitions of such a height that when the tool shank and the motor assembly are coupled, said retaining click-in piece is finally housed in one of the hollow inner sectors of the coupling bell, the force of the elastic give being sufficient to keep the tool shank coupled without the possibility of accidental releases thereof, whilst its strength is such that it allows any user to release the tool shank with a simple untwisting movement. Moreover, the provision of the elastic retaining click-in piece simultaneously constitutes a means of “notifying” the user that the parts have been fully fitted together, thanks to the click that is heard whenever the piece is pushed into place over the corresponding partition of the coupling bell as the tool shank is being screwed onto the motor assembly.
As will be understood, with a coupling arrangement designed in such a way as that described above, not only does it ensure a correct positioning of one part (the tool shank) in relation to the other (the motor assembly), but also the user is aware at all times that the blender is being used correctly and safely.